1. Field of the Invention
The present invention relates to drilling devices and more particularly to a roof bolt hole groover which cuts grooves simultaneously as the hole is drilled.
2. Description of the Prior Art
In mining, it is often necessary to bolt together a discontinuous rock mass in order to provide a safe mine roof. This is normally accomplished by roof bolting. There are two popular methods of roof bolting, namely point-anchored (or tensioned) and full-length anchored (or nontensioned) bolting. A point-anchored bolt is a bolt anchored at the extreme end located in a roof bolt hole drilled into the rock mass and having a bearing plate connected at the other end of the bolt located at the collar of the hole. On the other hand, a full-length anchor bolt is a bolt grouted with resin or the like throughout the roof bolt hole.
With present devices a roof bolt hole is drilled into a rock mass and a smooth bore hole surface results. The anchoring capacity of the full-length anchor bolt, usually a resin bolt if resin is used, can be enhanced by making the roof bolt hole surface rough. Therefore, rifling tools were developed to scratch or groove the roof bolt hole surface. The roof drilling operation using such a rifling tool required two steps: first step being to drill a hole in the rock mass and the second step to cut rifle grooves in the bore hole surface. The groove inervals and depth are not easily controllable with the presently used rifling tools.
The present invention ameliorates the aforementioned problems of the prior devices by providing a roof bolt hole groover which cuts grooves in the wall hole surface simultaneously as the hole is being drilled.